Heretofore, many macromolecular materials have been used as medical materials. Cellulosic materials are especially widely employed because of their safety, processability and economic advantages. On the other hand, biocompatibility is a problem in the use of those macromolecular materials. Especially problematic are such common properties of macromolecular materials as coagulating blood or activating immune system when used for the devices that will come in contact with blood. In order to improve blood coagulative activity of macromolecular materials a method in which cellulose is connected with heparin, for example, has been proposed (Japanese Patent Application Laid-Open-to-Public No. 57288/1978). However, the method is not satisfactorily effective, and development of more improved medical materials is desired.